"We love how the rooms and floors are always a comfortable temperature. It's a very low cost to run and we barely think about it."

Wanaka location, 250 sq/m floor size, 4 occupants
Our client built their new home with some specific requirements in mind. They were looking for ambient, comfortable heat throughout the entire house without the high electricity bills that came with their last home (running an air-to-air heat pump). The client was particularly interested in an environmentally friendly solution and had researched a ground source (geothermal) heating system. We organised the specific system design, e.g. heating calculations and got the job done. The house was designed with passive heating principles and good insulation to ensure system efficiency.
Groundsource (geothermal) heating works by water flowing through a series of pipes run below ground (called slinkys). The natural ground temperature heats the water which then passes through a heat pump to increase the temperature to a point it can be used for the central heating. As the earth temperature remains at a constant, the ground source heat pump is not affected by extremely cold temperatures. Due to the high efficiency of the system and lack of fossil fuels used to heat the water, a ground source system is considered to be one of the most environmentally friendly forms of heating. 
> 16kw Kensa Ground Source Heat Pump
> Underfloor Heating (7 zones)
> Heatmiser Neostat Thermostats x 7
> Radiator x 1
> Wood Fire

The house is divided into 7 underfloor heating zones. This system is controlled by the programmable Neostat thermostats, which are located in each underfloor heating zone. When the air temperature in the underfloor heating zone drops below the set temperature on the thermostat, at the set times on the thermostat, the underfloor heating will come on. 

This system also has a radiator located in the laundry, rather than underfloor in this area. The radiator is controlled by another Neostat thermostat and the thermostatic radiator valve (TRV) located on the radiator). 

The wood fire located in the lounge is primarily for ambience rather than a heat source. Our client hasn't bought any new wood in over 2 years. In winter, they occasionally light the fire if they want a direct heat source, or 'top up'.

> Domestic hot water could also be incorporated into this system, so the central heating and domestic hot water is from the same heat source. 
> A Heatmiser Neohub and NeoApp (smartphone application) could be installed so the client controls the system operation (e.g. turning on/off, adjusting set temperatures) from their smartphone. 
> Solar PV could be installed to offset some of the electricity costs during winter (e.g. credit is built up over summer months to use over winter when the central heating pushes the electricity bill higher). As buy back rates in NZ are quite low this doesn't always balance out depending on the clients usage.
Our clients largest electricity bill was around $400 for the month of June. The heat pump is a highly efficient method of water heating, making the system comparatively very low cost to run with a higher capital cost.
> Technician maintenance - all central heating systems should be serviced annually to maintain efficiency. An average heat pump service costs $250 + GST. 
> Client maintenance - the pressure in the system needs to be kept topped up for the system to operate. Occasionally, this may drop and need to be topped up. This is a 10 minute task and we provide our clients with an manual specific to their system with instructions on how to do this. 
"The Optum team were really great when we were planning our new home and clearly understood the reasons we wanted a groundsource/underfloor solution. They worked well with both our designer and builder and we're really stoked with the result. The house is warm and comfortable and the system works as promised. It's low cost to run and environmentally friendly too!" 
"We love how the rooms and floors are always a comfortable temperature. It's very low cost to run and we barely think about it. We used to be concerned about running the air source heat pump in our old house as it used a lot of power, but now we don't have to worry about it. I would simplify the operating system/app. I still find that confusing but because we just leave it at a constant temperature, it's not something I have to think about much."

Download information sheet on how groundsource heating works by our heat pump supplier, Kensa.


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